1990 AE92 sedan....weird problem - Toyota Nation Forum : Toyota Car and Truck Forums

bcp477 · 06-06-2010, 09:25 PM

Ok, I've got a good one for you guys. In just the last couple of days, a problem has developed with my car...which I am at a loss to figure out, so far. I'd be grateful for any insight you guys might have on this.

Except for this issue, which occurred once on Friday and once on Saturday....the car runs flawlessly. Here are the particulars..... after driving the car extensively....and it being fully warm....the car (so far, twice) stumbles once or twice, while at idle....then stalls. It will not restart, despite turning over just fine and making no strange or disturbing noises or other signs of major problems. After about 20 minutes or so, the car will start as normal....and can be driven normally ...just like nothing ever happened.

I had the car transported to a shop, after the first time it happened....and they have no idea....and could not make the problem occur again. Neither could I, after spending hours with it, last night and today. Apparently, the problem will only occur after the car has been driven awhile....and only when idling, such as at a traffic light.

Let me tell you what this is NOT...or so would be indicated from my checking things so far. The igniter and coil pack check out fine. The distr. rotor, plugs, cap and wires are fine. I just replaced the temp. sensor, as well as the fan switch and dash temp sending unit a short time ago. I have not replaced the cs injector time switch....as it is an expensive little sucker. Interestingly, when the car stalled last night, I had the cs injector and time switch unplugged....in case the problem might be with the cs circuit. The fuel pump and pressure check out fine, so I expect the fuel pressure regulator is OK, as well. Ground straps are OK. I pulled the cs injector today....and it was pretty clean, with no sign of problems. It definitely isn't stuck open, as I suspected.

As I said, except for this intermittent glitch...the engine has been running flawlessly. I suspect flooding is the cause...but I can't confirm this yet. The next time it happens, I will pull a sp plug... straight away....and check for fouling.

So, any ideas, guys ? I' ve done a search of this forum....and read over everything I could...but so far, no help. I should add that the car did not stall today, despite driving a good bit. However, on theory that the problem is due to flooding, I've been holding about 2000 rpm at traffic lights.

bcp477 · 06-06-2010, 09:31 PM

Oh, a couple more things I forgot to mention. NO error codes in the computer....and I can't find any vacuum leaks. No fuel leaks, either. I replaced all of the vac hoses and fuel lines a couple of months ago....nevertheless, I checked everything for leaks.

bcp477 · 06-06-2010, 09:41 PM

Oh, also..... timing belt is good. The engine is timed correctly and idle speed is set correctly. The engine idles smoothly....

90 GP · 06-07-2010, 06:29 AM

Carry a can of starting fluid in the car. When it does it again immediately remove air intake and give it a good shot of fluid and try to start it. If it starts , runs and stalls when fluid is burned you have a fuel delivery problem (intermittent fuel pump or pinhole in fuel line). If it doesn't then it's an ignition problem as in ignition coil etc.

SuperRA · 06-07-2010, 11:10 AM

I had a coil that would go out of spec when it got hot. Makes sense, when stuff gets hot it expands and if there's a bundle of wire where the insulation failed, they could start touching (inside the coil). So I guess I'm saying you have to test the coil once the failure occurs at the right temp.

Plasma_Jet · 06-07-2010, 05:43 PM

Torque Convertor Clutch (TCC) solenoid
might want to look in that direction, happens in the conditions you describe and you haven't checked there yet. hope its help or shines light on the issue.

bcp477 · 06-08-2010, 12:20 PM

Ok, thanks for the suggestions. The heat-related electrics issue had occurred to me.....and fits with the time delay in getting the car restarted....but it does NOT make sense that the problem can't be duplicated by just idling the car for a long period. Heat is heat, after all. But, anything is possible....I can't dismiss any possibility at this point.

As for the torque converter switch....the car has a manual tranny (which I forgot to mention in the first place) ....so I think it does not apply. Thanks for the effort, though.

Finally, the problem has not reoccurred since Sat. Yesterday, after driving home, I readjusted the throttle positioner....and reset the idle....so that the car "idles" at about 1200 rpm. I had been holding the car at 1500 - 2000 rpm at traffic lights....so this is easier. The car has not missed a beat since I began not allowing it to truly idle....but that could be incidental. Now I am wondering about the vac advance, etc. If that goes interrmittently wacky....it could cause stalling and make the car hard to restart. Anyway, I'll keep my eye on it and report back whatever I find.